I find my shopping bill each week is more if i'm not on plan as i fill my trolly with lots of crisps and chocolate and jelly sweets and cakes and biscuits etc and it adds up, not to mention my wine for the weekend. If i'm on plan, i replace all of the above with fruit and i don't find it to be any more expensive. I buy frozen sprouts brocolli and cauliflour too, as i find it cheaper for more, but i buy fresh carrots turnips and onions. With meat i normally get it from my local butchers, i thought it would be a lot more expensive to start with but it isn't. You get much more for your money i find so it lasts longer. when i get paid i buy mince, chicken breasts, some bacon and a big chicken and i stick them in the freezer when i get home and just use as and when i want. The large chicken does my family of 4 for 2 days, i would have a roast dinner, then with the chicken that's left i would do a curry. Sometimes i would use the stock for a pot of soup. So two main meals for a family of 4 plus a big pot of soup with the stock that can be frozen and last a while. I can normally get my shopping for between 60 and 70 per week for the four of us, but that includes the non food stuff too.
Also if i buy bananas from morrisons i used to get the ones that were in the packaging for about £1.20 for about 6 or 7, i have just discovered that if you get them with no packeging they are a lot cheaper, i got 6 big bananas for about 64p at the weekend